/**
 * Copyright (c) 2005-2012 springside.org.cn
 */
package com.gitee.fdc.kits;

import java.io.PrintWriter;
import java.io.StringWriter;

import javax.servlet.http.HttpServletRequest;

/**
 * 关于异常的工具类.
 * 
 * @author calvin
 * @version 2013-01-15
 */
public class Exceptions {

    /**
     * 将CheckedException转换为UncheckedException.
     */
    public static RuntimeException unchecked(Exception e) {
	if (e instanceof RuntimeException) {
	    return (RuntimeException) e;
	} else {
	    return new RuntimeException(e);
	}
    }

    /**
     * 将ErrorStack转化为String.
     */
    public static String getStackTraceAsString(Throwable e) {
	if (e == null) {
	    return "";
	}
	StringWriter stringWriter = new StringWriter();
	e.printStackTrace(new PrintWriter(stringWriter));
	return stringWriter.toString();
    }

    /**
     * 判断异常是否由某些底层的异常引起.
     */
    public static boolean isCausedBy(Exception ex, Class<? extends Exception>... causeExceptionClasses) {
	Throwable cause = ex.getCause();
	while (cause != null) {
	    for (Class<? extends Exception> causeClass : causeExceptionClasses) {
		if (causeClass.isInstance(cause)) {
		    return true;
		}
	    }
	    cause = cause.getCause();
	}
	return false;
    }

    /**
     * 在request中获取异常类
     * 
     * @param request
     * @return
     */
    public static Throwable getThrowable(HttpServletRequest request) {
	Throwable ex = null;
	if (request.getAttribute("exception") != null) {
	    ex = (Throwable) request.getAttribute("exception");
	} else if (request.getAttribute("javax.servlet.error.exception") != null) {
	    ex = (Throwable) request.getAttribute("javax.servlet.error.exception");
	}
	return ex;
    }

}
